Eficácia de diferentes materiais de barreira cervical na prevenção da penetração de peróxido de hidrogênio durante o clareamento de dentes não vitais: um estudo laboratorial in vitro

Abstract

Introduction: Internal dental bleaching is a conservative procedure indicated for the treatment of non-vital teeth presenting intrinsic discoloration after endodontic treatment. However, the diffusion of bleaching agents through dentinal tubules may reach the periodontal tissues and trigger complications such as external cervical resorption. Therefore, the use of an adequate cervical barrier is essential to limit hydrogen peroxide penetration and increase the biological safety of the procedure. Objective: To evaluate the sealing efficacy of different cervical barrier materials and their influence on hydrogen peroxide penetration and bleaching effectiveness during internal bleaching of non-vital teeth. Methods: One hundred and ten human single-rooted canines were endodontically treated and divided into 11 groups (n = 10) according to the cervical barrier material used: no barrier (positive control), Coltosol, zinc oxide-eugenol, zinc phosphate cement, selfadhesive cement, bioceramic cement, mineral trioxide aggregate (MTA), glass ionomer cement, resin-modified glass ionomer cement, flowable composite resin, and a negative control (no barrier, no bleaching). Internal bleaching was performed using 35% hydrogen peroxide in two sessions. Hydrogen peroxide penetration was quantified using UV-Vis spectrophotometry, and color change was evaluated at baseline and up to four weeks using a spectrophotometer, ΔE₀₀ and the Whiteness Index (WI). Results: Flowable composite resin, glass ionomer cement, resin-modified glass ionomer cement, MTA, and bioceramic cement significantly reduced peroxide penetration compared with temporary and zincbased materials (p < 0.00001). No significant differences in bleaching efficacy were observed among the barrier groups, and all materials promoted significant color improvement over time. The highest ΔE₀₀ and WID values were observed after four weeks (p = 0.0001). Conclusion: The type of cervical barrier material directly affects peroxide leakage during internal bleaching. Materials with adhesive or calcium silicate properties provided superior sealing without compromising aesthetic outcomes. Careful selection of barrier materials increases the safety and predictability of internal bleaching protocols. Clinical relevance: The appropriate selection of cervical barrier materials increases the safety of internal bleaching procedures while maintaining predictable aesthetic outcomes.